There are many different ways to do this, but the basic underlying structure will remain the same. You'll configure the switchport to be a member of an untagged VLAN (with it's associated DHCP scope) for the computer, and then tag the "voice" VLAN (with a different DHCP scope associated with it) for the phone traffic. The phone will be capable of separating the traffic based on the VLAN tag, and since you will be plugging the computer into the phone jack, you can let the phone do the magic for you. On an Enterasys switch the port commands would look something like this, where VLAN 300=data_VLAN, and VLAN 400=voice_VLAN:
set port vlan ge.1.1 300 no-modify egress
set vlan egress 400 ge.1.1 tagged
The XOS will be similar, and look something like this:
configure voice_VLAN add ports 1 untagged
configure data_VLAN add ports 1 tagged
I am admittedly less familiar with XOS (for now). Plug the phone into the switch, and your computer into the phone, and you should be on your way.